The ECB launched its €1.1 trillion bond-buying scheme - a form of monetary policy or quantitative easing - in January to support the eurozone economic recovery, which the bank's president, Mario Draghi, said could be extended beyond 2016 if needed.

Mr Schaeuble has repeatedly warned against an over-reliance on central bank stimulus to prop up economies.

He stressed the need for structural reforms stating: "When we call for structural reforms in return for financial assistance, this isn't some narrow-minded mantra being repeated by people who have lost sight of the big strategic questions of the future.

Pointing out the obvious, there's a financial bubble. Which was the policy aim wasn't it?